Urea solution pump structure

ABSTRACT

A urea solution pump structure may include a housing portion connected to an external connector and covering an upper portion of the pump structure, a motor portion disposed at a lower portion of the housing portion and including a rotor and a stator, a case portion receiving the motor portion therein, and a pump portion disposed at a lower portion of the case portion and fluid-isolated from the motor portion, wherein the pump portion may be formed with an inlet and an outlet for a fluid, wherein a hollow cover may be provided at a lower portion of the case portion for separating the pump portion and the motor portion, and an oil seal unit may be mounted at a lower portion of the hollow cover for sealing a rotating shaft of the rotor which penetrates through the hollow cover.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2011-0113265 filed in the Korean Intellectual Property Office on Nov. 2, 2011, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a urea solution pump structure. More particularly, the present invention relates to a urea solution pump structure used in a urea-SCR system in which a motor portion can be protected by effectively preventing a leakage of urea.

2. Description of Related Art

A vehicle can be classified by the type of the vehicle such as a sedan, bus, and truck. On the other hand, the vehicle can be classified by the type of fuel such as a gasoline vehicle using gasoline as fuel, a diesel vehicle using diesel as fuel, and a liquefied petroleum gas (LPG) vehicle even if the type of vehicle is the same.

It is more difficult to eliminate NOx in a diesel vehicle than a gasoline vehicle because diesel is burned in an excess oxygen state such as a lean burn state, and as a result, a lot of NOx is generated. Therefore, a urea selective catalytic reduction (urea-SCR) system is being developed as a main technology for eliminating NOx.

The urea-SCR system supplies urea (NH_(2—)CO—NH₂) as a type of aqueous solution, the urea solution is pyrolyzed into ammonia (NH₃) and isocyanic acid (HNCO) by a high temperature exhaust gas, and the isocyanic acid (HNCO) is hydrolyzed into ammonia and carbon dioxide by water of the exhaust gas. The ammonia generated by the above-mentioned method is used as a catalyst for changing NOx into N₂+O₂.

The urea-SCR system generally has an injector for injecting urea, a pump for supplying a urea solution in the urea tank to the injector, and a CPU for controlling an injecting pressure and an injecting time.

It is difficult to use a gasoline fuel pump or a diesel fuel pump used for a vehicle engine as a pump for supplying urea. Because the urea solution is a strong alkaline material (Ph 9-11), suit corrodes almost every metal except an SUS material.

As shown in FIG. 1, a conventional brushless direct current motor within a fuel pump (BLDC fuel pump) has a structure in which a fuel is pressurized by the pump rotation and the pressurized fuel is discharged from an upper end of a motor portion after passing through the motor portion.

Therefore, if the conventional fuel pump is used for a urea solution pump, a motor of the pump formed with copper or steel may be seriously damaged by the highly corrosive urea solution. An actual test showed that the conventional pump malfunctioned because of corrosion caused by the urea solution after 4 to 6 hours of operation.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing a urea solution pump structure having advantages of preventing corrosion caused by urea solution leakage, reducing manufacturing cost, and reducing noise.

In an aspect of the present invention, a urea solution pump structure may include a housing portion connected to an external connector and covering an upper portion of the pump structure, a motor portion disposed at a lower portion of the housing portion and including a rotor and a stator, a case portion receiving the motor portion therein, and a pump portion disposed at a lower portion of the case portion and fluid-isolated from the motor portion, wherein the pump portion is formed with an inlet and an outlet for a fluid, wherein a hollow cover is provided at a lower portion of the case portion for separating the pump portion and the motor portion, and an oil seal unit is mounted at a lower portion of the hollow cover for sealing a rotating shaft of the rotor which penetrates through the hollow cover.

The oil seal unit may include a fixed element mounted under the hollow cover and enclosing the rotating shaft of the motor portion, a rotating element fixed to the rotating shaft to rotate with the rotating shaft, a pressing element disposed under the rotating element and elastically biased toward the rotating element.

A damping space is formed between an interior circumference of the pump portion and the rotating element of the oil seal unit.

The oil seal unit is a mechanical seal.

A damping space is formed between an interior circumference of the pump portion and an exterior surface of the mechanical seal.

The pump portion may include a gear box being a main body of the pump portion, a gear pump mounted at a groove formed on a lower portion of the gear box, and a lower panel covering a lower surface of the gear box and formed with the inlet and the outlet, and the damping space is formed between an interior circumference of the gear box and the mechanical seal.

A filler is provided in the damping space for absorbing expansion of a urea solution.

The filler is compressible.

A drain hole is formed or a relief valve is mounted at a lower surface of the damping space in the gear box close to the inlet for preventing overpressure of the fluid.

The drain hole or the relief valve is formed between the damping space and the inlet and connected to the inlet.

A bearing is provided at an upper portion of the case portion for supporting the rotation of the rotating shaft.

The pump portion may include a main body portion which forms the damping space, a gear pump portion which is engaged at a lower portion of the main body portion and of which a gear pump is provided with therein, and a lower panel covering a lower surface of the gear pump portion and connecting to the gear pump portion being formed with the inlet and the outlet.

The urea solution pump structure according an exemplary embodiment of the present invention may reliably protect the motor portion from the urea solution by separating the motor portion from the pump portion and sealing the joint part of the motor portion and the pump portion by a mechanical seal.

Further, the present invention may prevent damage to the pump portion by forming a damping space between the mechanical seal and the pump portion.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a urea solution pump structure according to the conventional art.

FIG. 2 is an exploded perspective view of a urea solution pump structure according to an exemplary embodiment of the present invention.

FIG. 3 is a combined cross-sectional view of a urea solution pump structure according to an exemplary embodiment of the present invention.

FIG. 4 is a perspective view of an essential part of a urea solution pump structure according to an exemplary embodiment of the present invention.

FIG. 5 is a perspective view of an inner part of a urea pump structure according to an exemplary embodiment of the present invention.

FIG. 6 is a perspective view of an inner part of a urea pump structure according to another exemplary embodiment of the present invention.

FIG. 7 is a cross-sectional view of an inner part of a urea pump structure according to another exemplary embodiment of the present invention.

FIG. 8 is a perspective view of an inner part of a urea pump structure according to another exemplary embodiment of the present invention.

FIG. 9 is an exploded perspective view of a housing portion according to an exemplary embodiment of the present invention.

FIG. 10 is an exploded perspective view of a stator of a motor portion according to an exemplary embodiment of the present invention.

FIG. 11 is an exploded perspective view of a rotor of a motor portion according to an exemplary embodiment of the present invention.

FIG. 12 is an exploded perspective view of a case portion according to an exemplary embodiment of the present invention.

FIG. 13 is an exploded perspective view of a pump portion according to an exemplary embodiment of the present invention.

FIG. 14 is a cross-sectional view of a pump portion according to another exemplary embodiment of the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings.

FIG. 2 is an exploded perspective view of a urea solution pump structure 10 according to an exemplary embodiment of the present invention, FIG. 3 is a combined cross-sectional view of a urea solution pump structure 10 according to an exemplary embodiment of the present invention, FIG. 4 is a perspective view of an essential part of a urea solution pump structure 10 according to an exemplary embodiment of the present invention, and FIG. 5 is a perspective view of an inner part of a urea pump structure 10 according to an exemplary embodiment of the present invention.

As shown in FIG. 2 to FIG. 5, the urea solution pump structure 10 according to an exemplary embodiment of the present invention may include a housing portion 100 connected to an external connector and covering the upper portion of the pump structure, a motor portion 200 disposed at a lower portion of the housing portion and including a rotor 220 and a stator 210, a case portion 300 receiving the motor portion 200 therein, and a pump portion 400 disposed at a lower portion of the case portion 300 and formed with an inlet 441 and an outlet 442 for a fluid.

A hollow cover 310 is provided at a lower portion of the case portion 300 for separating the pump portion 400 and the motor portion 200, and an oil seal unit 320 is mounted at a lower portion of the hollow cover 310 for sealing a rotating shaft 221 of the rotor 220 which penetrates through the hollow cover 310.

The present invention protects the motor portion from corrosion by providing the hollow cover 310 and sealing the rotating shaft 221 of the rotor 220.

Further, the urea pump structure according to an exemplary embodiment of the present invention protects the motor portion 200 from the urea solution by separating the motor portion 200 and the pump portion 400, and forming both the inlet 441 and the outlet 442 at the pump portion 400 for making the urea solution pass through the inlet 441 and the outlet 442.

The housing portion 100 is an upper cover of the urea solution pump structure 10 and is connected to an external connector.

As shown in FIG. 9, the housing portion 100 may include a housing 110 forming a main body of the housing portion 100 and receiving the external connector therein, a printed circuit board (PCB) 120 mounted in the housing 110 and switching power, a first ring seal 130 for preventing leakage through the housing portion 100, and a terminal 140 applying an electric current and inserted into the external connector.

The housing 110 may be made with a PBT+GF30% material which has excellent insulation resistance and chemical resistance, the PCB 120 may be made with an FR-4 material which has heat resistance, moisture resistance, and high safety by layering glass fibers with an epoxy resin, the first ring seal 130 may be made with an H-NBR material having heat resistance, ozone resistance, and oil and fuel resistance, and the terminal 140 may be made with brass (C2680) having corrosion resistance, machinability, and easy plating ability.

The motor portion 200 may be composed of the stator 210 and the rotor 220.

The stator 210, as shown in FIG. 10, may include upper and lower insulators 211 and 214 for insulating, a magnet wire 213 for generating a magnetic field, and a stator core 212 with the magnet wire 213 wound around it as a laminated core.

The upper insulator 211 and the lower insulator 214 may be made with a PBT+GF30% material which has excellent insulation resistance and chemical resistance, the stator core 212 may be made with an S18 material having excellent relative permeability and that is generally used in a motor, and the magnet wire 213 may be made with an AIW material having ozone resistance and chemical resistance.

The rotor 220, as shown in FIG. 11, may include the rotating shaft 221, a magnet 222 disposed at the outside of the rotating shaft 221, a magnetic detector 223 for measuring a position of a hall sensor, and a push nut 224 for fixing the magnetic detector 223.

The rotating shaft 221 may be made with an SUS304 material which has corrosion resistance, machinability, and easy plating ability, the magnet 222 may be an ND-bonded magnet which has corrosion resistance and high safety, the magnetic detector 223 may be made with a plastic magnet material having machinability and shock resistance, and the push nut 224 may be made with stainless steel used for a spring.

The case portion 300, as shown in FIG. 12, may include the hollow cover 310 provided at a lower portion of the case portion 300, the oil seal unit 320 mounted at a lower portion of the hollow cover 310 for preventing leakage of a fluid, and a bearing 330 provided at an upper portion of the case portion 300 for supporting the rotation of the rotating shaft 221.

The hollow cover 310, as shown in FIG. 6 and FIG. 7, separates the pump portion 400 and the motor portion 200 by being mounted at the upper position of the pump portion 400. A second ring seal 340 may be adapted at the joint part of the hollow cover 310 and the pump portion 400 for preventing leakage.

In one or a plurality of exemplary embodiments, as shown in FIG. 6 and FIG. 7, the lower surface of the cover 310 may have a concave structure, and the oil seal unit 320 may be inserted into the concave structure of the cover 310.

The oil seal unit 320 prevents leakage of a urea solution between the motor portion 200 and the rotating shaft 221 by being closely formed to the exterior circumference of the rotating shaft 221

The oil seal unit 320 prevents the urea solution from flowing into the motor portion 200 from the gap between the motor portion 200 and the rotating shaft 221 by being closely disposed to the exterior circumference of the rotating shaft 221.

In one or a plurality of exemplary embodiments, the oil seal unit 320 may be a mechanical seal.

A mechanical seal is generally used to prevent leakage of a fluid from a rotating shaft at a high temperature and high pressure. In general, the mechanical seal has a rotating element for rotating with a shaft and a fixed element fixed at a body, and the rotating element and the fixing element are closely formed with each other so as to move with respect to each other while maintaining an airtight and watertight seal at the contact surface.

In one or a plurality of exemplary embodiments, as shown in FIG. 6 and FIG. 7, the mechanical seal 320 may include a rotating element 321 rotating with the rotating shaft 221 of the motor portion 200, and a fixed element 322 fixed at the hollow cover 310. A pressing element 323 such as a coil spring may be provided at the back of the rotating element 321 so as to contact the rotating element 321 and the fixed element 322 evenly by pressing the rotating element 321 toward the fixed element 322, such that leakage between the rotating element 321 and the fixing element 322 may be effectively prevented by the force of the pressing element 323 and a force of hydraulic fluid in the mechanical seal.

As shown in FIG. 3 and FIG. 5, the bearing may be provided at the upper portion of the case portion for supporting the rotation of the rotating shaft. As shown in FIG. 3, the magnetic detector 223 of the motor portion 200 may be disposed at the upper portion of the bearing 330.

In one or a plurality of exemplary embodiments, as shown in FIG. 13, the pump portion 400 may include a gear box 420 being a main body of the pump portion 400, a gear pump 430 mounted at a groove formed on a lower portion of the gear box 420, and a lower panel 440 covering a lower surface of the gear box 420 and formed with the inlet 441 and the outlet 442.

The motor portion 200 is protected from corrosion by the urea solution since both the inlet 441 and the outlet 442 are formed at the lower panel 440 of the pump portion 400 such that the urea solution cannot flow into the upper side of the pump portion 400.

A damping space 410 may be formed between the interior circumference of the gear box 420 and the mechanical seal 320.

If the urea solution leaks from a gap between the rotating shaft 221 and the pump portion 400 following the arrow direction shown in FIG. 3, the damping space 410 receives the urea solution having leaked from the gap. The urea solution having leaked from the gap has no place to be received if the damping space 410 is not formed between the interior circumference of the gear box 420 and the mechanical seal 320 such that the pump portion 400 may be damaged by freezing distension of the urea solution when the temperature drops. Therefore the damping space 410 plays a role in preventing damage to the pump portion 400.

As shown in FIG. 6, a compressible filler 411 such as silicon may be spread or attached in the damping space 410 for absorbing the expansion of the urea solution. If the filler 411 is provided in the damping space 410, the pump portion 400 may be protected by the filler since the filler 411 makes room for absorbing the freezing distension of the urea solution even when the urea solution is filled in the damping space 410.

A drain hole 421 may be formed or a relief valve may be mounted at a lower surface of the gear box 420 of the side where the inlet 441 is located for preventing overpressure caused by pumping the urea solution. As shown in FIG. 8, if the urea solution is excessively pressurized, the urea solution is discharged toward the B direction by passing through the drain hole 421 or a relief valve. Therefore, the pump portion 400 is protected from an excessively high pressure by the drain hole 421 or the relief valve.

As shown in FIG. 13, the gear pump 430 may be mounted in a groove which is formed at the bottom of the gear box 420. The gear pump 430 may be a pump that inversely discharges a fluid by counter rotation. An internal gear pump, an external gear pump, a roller cell pump, or a geroter pump may be used as the gear pump 430 according to a situation.

As shown in FIG. 5, a third ring seal 450 and a fourth ring seal 451 may be provided between the gear box 420 and the lower panel 440 for preventing leakage of fluid pumped by the gear pump 430.

FIG. 14 is a cross-sectional view of the pump portion according to another exemplary embodiment of the present invention.

As shown in FIG. 14, the pump portion 400 a according to another exemplary embodiment of the present invention includes a main body portion 460 which forms the damping space 410, a gear pump portion 470 which is engaged at a lower portion of the main body portion 460 and of which a gear pump 430 is provided with therein, and a lower panel 440 covering a lower surface of the gear pump portion 470 and connecting to the gear pump portion 470 being formed with the inlet 441 and the outlet 442.

The main body portion 460 forms the damping space 410 and the mechanical seal 320 is provided with therein.

The gear pump portion 470 of which the gear pump 430 is provided with therein is separated from the main body portion 460, as a result a size of the gear pump portion 470 can be easily changed according to a type or a size of the gear pump 430.

As shown in FIG. 14, the gear pump portion 470 may be formed in shape of a plate of which the gear pump 430 is provided with therein. As a result the pump portion 400 is divided into three layers and it becomes easy to change a size or a gap of the pump portion 400.

The urea solution pump structure 10 according the exemplary embodiment of the present invention may reliably protect the motor portion from the urea solution by separating the motor portion 200 from the pump portion 400 and sealing the joint part of the motor portion 200 and the pump portion 400 by the oil seal unit 320 such as a mechanical seal.

Further, the present invention may prevent damage to the pump portion 400 by forming the damping space 410 between the mechanical seal 320 and the pump portion 400.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

What is claimed is:
 1. A urea solution pump structure, comprising: a housing portion connected to an external connector and covering an upper portion of the pump structure; a motor portion disposed at a lower portion of the housing portion and including a rotor and a stator; a case portion receiving the motor portion therein; and a pump portion disposed at a lower portion of the case portion and fluid-isolated from the motor portion, wherein the pump portion is formed with an inlet and an outlet for a fluid, wherein a hollow cover is provided at a lower portion of the case portion for separating the pump portion and the motor portion, and an oil seal unit is mounted at a lower portion of the hollow cover for sealing a rotating shaft of the rotor which penetrates through the hollow cover.
 2. The urea solution pump structure of claim 1, wherein the oil seal unit includes: a fixed element mounted under the hollow cover and enclosing the rotating shaft of the motor portion; a rotating element fixed to the rotating shaft to rotate with the rotating shaft; a pressing element disposed under the rotating element and elastically biased toward the rotating element.
 3. The urea solution pump structure of claim 2, wherein a damping space is formed between an interior circumference of the pump portion and the rotating element of the oil seal unit.
 4. The urea solution pump structure of claim 1, wherein the oil seal unit is a mechanical seal.
 5. The urea solution pump structure of claim 4, wherein a damping space is formed between an interior circumference of the pump portion and an exterior surface of the mechanical seal.
 6. The urea solution pump structure of claim 5, wherein the pump portion includes a gear box being a main body of the pump portion, a gear pump mounted at a groove formed on a lower portion of the gear box, and a lower panel covering a lower surface of the gear box and formed with the inlet and the outlet, and the damping space is formed between an interior circumference of the gear box and the mechanical seal.
 7. The urea solution pump structure of claim 6, wherein a filler is provided in the damping space for absorbing expansion of a urea solution.
 8. The urea solution pump structure of claim 6, wherein the filler is compressible.
 9. The urea solution pump structure of claim 7, wherein a drain hole is formed or a relief valve is mounted at a lower surface of the damping space in the gear box close to the inlet for preventing overpressure of the fluid.
 10. The urea solution pump structure of claim 9, wherein the drain hole or the relief valve is formed between the damping space and the inlet and connected to the inlet.
 11. The urea solution pump structure of claim 1, wherein a bearing is provided at an upper portion of the case portion for supporting the rotation of the rotating shaft.
 12. The urea solution pump structure of claim 5, wherein the pump portion includes a main body portion which forms the damping space, a gear pump portion which is engaged at a lower portion of the main body portion and of which a gear pump is provided with therein, and a lower panel covering a lower surface of the gear pump portion and connecting to the gear pump portion being formed with the inlet and the outlet. 